How to setup upstart: When Cron isn’t enough

Reaching the limits of Cron

If you’re reading this blog post on account of the title, hopefully you already have a good understanding of what Cron is and you may well also be aware of some of it’s limitations. There are some situations when Cron use simply becomes impractical; the Cron minimum timeout of 1 minute can be prohibitively long to wait, rendering Cron an unhelpful tool for that particular project or situation.

In such moments I use Linux Upstart. It can run your code without a timeout at all or you can choose to set the timeout that you need.

Setting up Upstart

It’s very simple to set this up. To make a Symfony command I use daemonizable-command and write something like this:

	namespace …\Command;

	use Wrep\Daemonizable\Command\EndlessContainerAwareCommand;
	use Symfony\Component\Console\Output\OutputInterface;
	use Symfony\Component\Console\Input\InputInterface;

	use Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand;
	use Symfony\Component\Console\Input\InputArgument;
	use Symfony\Component\Console\Input\InputOption;

	class UpdateCommand extends EndlessContainerAwareCommand {

	protected function configure() {
	parent::configure();

	$this
	->setName(‘<some name>')
	->setDescription(‘<some description>')
	->setHelp( "Use -q to suppress all output \n
	Use --run-once to only run the command once, usefull for debugging \n
	Use --detect-leaks to print a memory usage report after each run, read more in the next section" )
	->setTimeout(0.5); //set timeout what your need
	}

	protected function execute(InputInterface $input, OutputInterface $output)
	{
	// here your code, if you need more timeout in some cases use “sleep(<time>)”
	}

	}

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Configuration

After that you’ll need to add an Upstart configuration file in Ubuntu.

The file extension should be “conf” eg,“project-task.conf”. Put the file into /etc/init/ or $HOME/.init/

	description “<some description>"
	author “<autor name, email etc.>”

	start on (local-filesystems and net-device-up)
	stop on shutdown

	console log
	respawn
	respawn limit 5 60
	exec project-url/app/console <commend name> -e prod —no-debug

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You can find more configurations here.

Control

Now you can control your command like a Ubuntu service:
service <project-task> status/stop/start/restart

Bonus

And for more usability I’ve written a small task for checking the status of and restarting these Upstart tasks. This one’s run by cron 🙂

	class DaemonCheckCommand extends ContainerAwareCommand {

	protected function configure() {
	parent::configure();

	$this
	->setName('daemon-check')
	->setDescription('Check daemons if it crased restarted it');
	}

	protected function execute(InputInterface $input, OutputInterface $output)
	{
	$status= false;

	$check = `echo ‘<password for this sudo user >' \| sudo -S status <task name>`;

	if ( strpos($check, 'start/running') === false ) {
	$startingCheck = `echo '<password for this sudo user >' \| sudo -S start <task name>`;
	if ( strpos($startingCheck, 'start/running') === false ) {
	$status .= "fail to start <task name> \n";
	} else {
	$status .= "restarted <task name> \n";
	}
	}

	if ( $status ) {
	$to = array(
	'email' => ‘name',
	…..
	‘email-n' => ‘name-n'
	);

	$message = \Swift_Message::newInstance()
	->setSubject('Project daemon crashed')
	->setFrom(array('support@project.com' => 'Project'))
	->setTo($to)
	->setContentType("text/html")
	->setBody(date('Y-m-d H:i') ."\n". $status);
	$this->getContainer()->get('mailer')->send($message);
	}
	$this->getContainer()->get( 'logger' )->err('---Daemon Check = ' . ($status ? $status : (date('Y-m-d H:i') . ' working')) );
	return $status;
	}

	}

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I hope this makes your life easier 😉